Articles->Building Trends->Engineered Wood Products

All Aboard
An Engineered Wood Primer
by Josh Kimball

You can help save our forests when you build your new home. How? Use engineered wood.

Photo courtesy of Georgia-Pacific

Engineered wood is a family of construction materials similar to traditional lumber, but made of smaller pieces of wood bonded together using the latest technology and innovation.

Why do we need engineered wood? Because many in the timber industry are conscious of the concerns of those who claim too many wood-framed houses are depleting North America's forests. So new ways are being developed to use as much of the wood from a tree as possible.

Environment
One might wonder what can be environmentally friendly about cutting down trees to make engineered wood products (EWPs). EWP companies are able to use quick-growing trees with a small diameter, rather than "old growth" or virgin forests, which many argue should be protected for future generations. Producing traditional, or "dimension," lumber requires the harvesting of mammoth trees in order to get many pieces of long, wide lumber that are suitable for construction. Conversely, engineered wood is made up of smaller pieces of the trees. "Engineered lumber is produced from 35 percent less timber and can be made from young, rapidly grown trees," explains Ken Galubinski of Georgia-Pacific. Since younger trees may be used, the aged trees are left intact. Another advantage is the fact that very little of each tree is discarded. So the process of making engineered wood products is highly efficient, minimizing waste.

History
Engineered wood products aren't new. In fact, the earliest EWP, plywood, dates back about 100 years. Glued laminated timber (glulam) has a fairly long history as well. But other engineered wood products, such as I-joists and laminated veneer lumber (LVL), surfaced in the mid-1970s. Even so, it was not until the early 1980s that engineered wood became widely accepted.

Its popularity continues today, as the industry discovers new ways to apply technology to produce materials that, in many cases, are preferable to solid wood. Builders and consumers seem to have caught on, as evidenced by the fact that the sales of engineered wood products have doubled every five years over the past two decades.

Photo courtesy of Georgia-Pacific

Process
The actual process of making engineered wood involves bonding together wood strands, veneers, lumber or other forms of wood fiber to produce a larger and integral composite unit.

"Engineered" applies to EWPs in that they undergo extensive testing to determine and increase their strength and other properties as they compare to solid wood.

General advantages
One of the greatest benefits of engineered wood is that it is generally stronger than traditional lumber, allowing wider spacing of joists, to save both material and time. Engineered wood is easier to work with than traditional dimension lumber, with every piece being lighter in weight and consistently true to size.

As mentioned above, engineered wood is environmentally sound, produced from 35 percent less timber, and made from young, rapid-growth trees. In addition, engineered wood has a high level of quality, resisting shrinking, crowning, twisting and warping, which, for example, results in quieter floors.

Galubinski also notes, "Engineered lumber provides more surface area for gluing and nailing; more mass under the floor to reduce vibration; tighter tolerances, which gives you a more level floor; and proven predictability."

Photo courtesy of Georgia-Pacific

Structural uses
Although some decorative uses of engineered wood products exist, the major uses of EWPs in construction involve such structural members as I-joists, beams, headers, rim boards and panels. Here is a brief explanation of these products:

I-joists: Engineered wood I-joists, or I-beams, are used extensively in floor and roof framing and span longer distances than solid lumber framing, replacing such dimension lumber as 2x10s and 2x12s.

I-joists are exceptionally stiff, for quieter floors. In addition, they are lightweight, easy to handle and uniform in size.

Photo courtesy of Georgia-Pacific

Oriented strand board: Oriented Strand Board (OSB), a replacement for traditional plywood, can be used anywhere plywood would be used, such as in roofs, walls or two-layer subfloor systems.

When it comes to structural panel construction, OSB is growing in popularity, relative to plywood. The reasons for this shift are many, including OSB's low cost, higher quality and environmental friendliness.

Glued laminated timber: Glulam is the most cost-competitive of the engineered wood products. Glulam beams are commonly used as roof beams, floor beams and headers because of their ability to span long distances and support heavy loads.

Glulams may also be used for columns, girders and deck panels.

Glued laminated timber can attain a one-hour fire rating, meaning that a fire would burn through the wood slowly enough that firefighters could salvage most of the home. This is a very attractive feature for insurance companies.

Laminated veneer lumber: "Widely used for headers and beams, laminated veneer lumber (LVL) eliminates the need for steel beams in residential construction," says Bill Rouleau of the Structural Wood Corporation.

A big advantage here is that LVL does not experience nearly the same twisting, splitting, checking, crowning and warping that solid wood beams do. Because LVL is made from veneers arranged in a specific pattern and bonded together, the resulting beams are strong, solid and straight.

Photo courtesy of Georgia-Pacific

Rim boards: A rim board is defined by the APA—The Engineered Wood Association as "the wood component that fills the space between the sill plate and the bottom plate of a wall, or, in second-floor construction, between the top plate and the bottom plate of two wall sections." In other words, rim boards look like a belt going around the middle of the house as it is being built.

Rim boards can be made using OSB, glulam or LVL. Advantages include less shrinkage than lumber and availability in lengths of up to 24 feet.

Structural insulated panels: Composed of a plastic foam core bonded to faces of wood structural panels, structural insulated panels (SIPs) can be used in place of traditional framing, sheathing and insulation in floor, wall and roof applications.

Advantages include high insulation values, strength, stiffness and fast, easy assembly.

Decorative uses
Although engineered wood products are largely used for structural applications in construction, they do have some decorative uses as well.

Exterior uses of EWPs are mostly in the area of trim around entries and under eaves.

Interior applications of EWPs include mouldings, cornices, fireplace surrounds and paneling, as well as furniture, cabinets, flooring, stair treads and shelving. These uses run the gamut from historically traditional styles to avant-garde contemporary.

The Composite Wood Council notes that "architects are . . . teaming versatile, economical products such as medium density fiberboard (MDF) with eye-catching paints and dyes to create striking, color-drenched focal points."

Summary
Wood construction of homes will not likely slow down as we move into the future--but neither will our desire to preserve our ancient forests. So it seems like a win-win solution to make use of engineered wood products, which offer the strength and durability of traditional lumber without sacrificing the trees with tradition.

Sources: APA—The Engineered Wood Association, Tacoma, Wash.; Composite Wood Council, Gaithersburg, Md.; Mark Englund, LifeStyle HomeDesign Services, St. Paul, Minn.; Ken Galubinski and Charlotte Wood, Georgia-Pacific, Atlanta, Ga.; Louisiana-Pacific®, Portland, Ore.; Bill Rouleau, CSI, Structural Wood Corporation, St. Paul, Minn.; Structural Board Association, Willowdale, Ont., Canada; Willamette Industries, Inc., Tualatin, Ore.

Â